Frequency multiplier

ABSTRACT

The invention can be used for telecommunications, measuring and other devices in order to produce stable superhigh frequency signals. An IMPATT diode ( 4 ) operating in the cascade break-down mode and having a sharp nonlinearity transforms an input signal in such a way that ultraharmonics which multiple in respect to the frequency of an input signal ω 0  occur in a frequency spectrum. An output stage of a multiplier is used in order to separate an output nω 0  frequency and to suppress adjacent frequencies. In order to tune the output stage to the nω 0  frequency, a tuning plug ( 8 ) and short-circuiting pistons ( 13 ) are used. The tuning plug ( 8 ) is arranged above an upper electrod of the IMPATT diode ( 4 ) (inside the axis of the diode). The tuning plugs ( 13 ) make it possible to tune resonance capacitance to the nω 0  frequency and remove energy towards the output part of a T-bend in which a wave guide pass-band filter ( 15 ) is disposed. Said filter ( 15 ) is embodied in the form of sections of a waveguide ( 14 ) on whose E-plane a thin metallic diaphragm is arranged, said diaphragm being provided with windows ( 16 ) disposed along the axis of the waveguide. The inventive multiplier ensures high converting efficiency.

The invention refers to electronics and can be used fortelecommunications, measuring and other devices in order to producestable superhigh frequency signals.

PREVIOUS TECHNICAL LEVEL

In order to solve a number of problems occurring in telecommunicationsand measuring, high-frequency sources, stable in amplitude, frequencyand phase, with a power ranging in decades of milliwatts are required tobe used. Known sources which use the principle of frequencymultiplication due to nonlinearity between the voltage applied to adiode and the current flowing through it, make it possible to produce anoutput signal with a multiplication ratio not exceeding 10 and outputfrequency not exceeding 40 GHz.

Known is a frequency multiplier containing an inlet filter to whoseoutlet a multiplier diode is connected, then comes a coupling elementwith the first end connected to the multiplier diode and the second endarranged in the output filter fitted in a section of an evanescentwaveguide with conducting open-circuit rods fixed on a wide wall insidethe waveguide in a way providing for trimming possibility, one of thesaid conducting open-circuit rods that is nearest to the multiplierdiode has an axial reach-through hole, and the coupling element isembodied in the form of an L-shaped conductor and is installed in such away that its second end is placed inside the axial hole out of contactwith its inner walls (1133K, 1681376).

Known is a frequency multiplier containing a pulse former, atime-to-code converter, a code-to-time converter and a clock-pulsegenerator, whose output is connected to the clock inputs of thetime-to-code converter and code-to-time converter, the first and secondoutputs of the pulse former are connected respectively to the clearinput and storage input of the time-to-code converter, the low-ordersignal output and high-order signal output are connected respectively tothe low-order signal input and high-order signal input of thecode-to-time converter, the pulse former input is the frequencymultiplier input, and the code-to-time converter is the output of thefrequency multiplier, the latter having a code-former connected inseries with a digital/analog converter which has its output connected tothe clock-pulse generator driving input, the code-former clear input isconnected to the first input of the pulse-former, and the data-signalinput of the of the code-former is connected to the low-order signaloutput of the time-to-code converter (USSR, 1695487).

Known is a frequency multiplier including an input circuit embodied as acoaxial connector for the input of signal to be multiplied, a means ofsupplying the signal to be multiplied to the IMPATT diode mounted in aretainer, a means of supplying dc bias voltage to the diode, and anoutput waveguide frame (U.S. Pat. No. 4,636,758).

Known devices have insufficient conversion efficiency and frequencymultiplication ratio.

DISCLOSURE OF INVENTION

This invention is based on a solution of the problem of creating afrequency multiplier with a multiplication ratio ranging from 3 to 30 ona frequency ranging from 20 to 180 GHz, to ensure an output power up to20 mW, at a limiting multiplication ratio.

The problem in view is solved owing to the fact that the frequencymultiplier including an input circuit embodied as a coaxial connectorfor the input of a signal to be multiplied, a means of supplying thesignal to be multiplied to the IMPATT diode mounted in a retainer, ameans of supplying dc bias voltage to the diode, and an output waveguideframe, is characterized by the fact that the means of the input of asignal to be multiplied is embodied as a microstrip line formed onpolycore wafer, and a gold-plated strip connected by welding to themicrostrip line and to the diode, the means of supplying dc bias voltageto the diode is embodied as a quarter-wave filter formed by themicrostrip inductance and capacitance, at that the output waveguidecircuit is embodied as a waveguide T-bend with an IMPATT diode arrangedin the centre and two short-circuiting pistons fitted in two oppositearms, the third arm allocating a waveguide pass-band filter.

The inventive solution has a number of additional features describingits special cases, specific forms of its physical embodiment, namely:

-   multiplier can be provided with a clamp to adjust the diode position    in the retainer using an a adjusting screw,-   multiplier can be provided with a tuning plug to be fixed in a    position in respect to the diode by means of a split terminal    consisting of a collet and a screw, and to be positioned over the    diode by means of a screw,-   multiplier can be provided with clamps to fix in a position the two    short-circuiting pistons located at the two opposite ends of the    T-bend,-   the waveguide pass-band filter is embodied as two equal waveguide    sections with a metal diaphragm nipped between them, and also    provided with windows disposed along the axis of the waveguide which    is formed by the said sections.

The applicant has not detected any sources containing information onengineering solutions identical to the present invention which allows todraw a conclusion on its compliance with the novelty criterion (N).

High multiplication ratio in the range of superhigh frequencies isattained in the suggested engineering solution due to the inventivedesign features and an effective input frequency matching of the devicecomponents.

The applicant is not aware of any publications containing information onthe effect of the inventive features on the technical result achieved.Therefore, it may be concluded, in the applicant's opinion, that thisengineering solution complies with the inventive step criterion (IS).

ABSTRACT OF DRAWING FIGURES

The essence of the invention is illustrated by the drawing, where

FIG. 1 shows the section of the device in the plane of the IMPATT diodecenter line,

FIG. 2 shows the section of the device in the plane perpendicular to theIMPATT diode center line with fragments of the,

FIG. 3 shows the same with the removed top closure head.

BEST OPTION OF THE INVENTION EMBODIMENT

The frequency multiplier includes a coaxial connector 1 to input asignal to be multiplied, a microstrip line 2 formed on the polycorewafer 3, which makes it possible to adjust the diode 4 to optimummatching of input frequency ω₀ by setting additional loopbacks (chips)on the polycore microstrip board, a gold-plated strip 5 connected bywelding to the upper electrode of the diode 4. The position of the diode4 located in the retainer 6 is regulated by means of the screw 7. Themeans of the output circuit adjusting for frequency ω₀ is embodied as atuning plug 8 mounted in a way to allow its relocating in respect to theIMPATT diode 4 by means of the screw 9 and arresting in respect to thediode by means of the split terminal 10. The means of supplying theIMPATT diode 4 with dc bias voltage is embodied as a quarter-wave filterformed by the microstrip inductance 11 and capacitance 12 inserted inthe slit of the microstrip line 2. The means of adjusting the outputcircuit to frequency ω₀ also includes two sliding short-circuitingpistons 13 which are fitted in the two opposite arms of the T-bend andare provided with clamps to fix them in a position. The third arm of theT-bend accommodates the waveguide pass-band filter which is embodied astwo sections of the waveguide 14 with a metal diaphragm 15 nippedbetween them and provided with windows 16 disposed along the axis of thewaveguide.

The device works as follows.

The frequency multiplication by means of IMPATT diodes is based on astrong nonlinear dependence between the voltage applied to the diode andthe current flowing through it at avalanching.

Three circuits can be found in the frequency multiplier:

-   1) input frequency circuit (ω₀ frequency to be multiplied),-   2) output frequency circuit (nω₀ frequency, where n is    multiplication ratio),-   3) fixed bias circuit.    The input and output circuits are coupled among themselves via    IMPATT diode nonlinearity in the cascade break-down mode.

The input signal ranging from 2 to 15 GHz is fed through a SMA coaxialconnector 1 which is soldered in the multiplier case. The input signalcomes to the IMPATT diode 4 through the microstrip line 2 connected tothe upper electrode of the diode 4 by means of the strip 5, whichensures a reliable contact and thermal stability of the multiplieroperation due to fastening method (welding) and thermostable materialwith a high conductance, such as gold, used for the strip manufacturing.The microstrip line 2 is also used to supply the diode 4 with the fixedbias voltage which comes through a bushing insulator in the multipliercase. The cd bias voltage and ac input signal are decoupled by using aquarter-wave filter formed by the microstrip inductance 11 andcapacitance 12 which is fitted in a breaking of the microstrip line 2 onthe polycore board 3. The IMPATT diode 4 in the retainer 6 is placed atthe centre of the T-bend which is formed in the multiplier case. Theupper electrode of the diode 4 is on a level with the upper surface ofthe microstrip board 3. The appropriate position is fixed with the screw7.

The IMPATT diode 4 operating in cascade break-down mode and having asharp nonlinearity transforms an input signal in such a way thatultraharmonics which multiple in respect to the input signal frequencyω₀ occur in the frequency spectrum. An output stage of a multiplier isused in order to separate an output nω₀ frequency and to suppressadjacent frequencies. In order to tune the output stage to the nω₀frequency, a tuning plug 8 and short-circuiting pistons 13 are used. Thetuning plug 8 is arranged above an upper electrode of the IMPATT diode 4(inside the axis of the diode). The tuning plug position above the diodeis regulated with the screw 9 and fixed with the collet 10. The tuningplugs 13 make it possible to tune resonance capacitance to the nω₀frequency and remove energy towards the output part of a T-bend in whicha wave guide pass-band filter 15 is disposed. Said filter 15 is embodiedin the form of sections of a waveguide 14, on whose E-plane a thin metaldiaphragm is arranged, said diaphragm being provided with windows 16disposed along the axis of the waveguide.

The inventive multiplier design using n*-n-p* diode in cascadebreak-down mode as a nonlinear element ensures high convertingefficiency, which makes approximately 1/n. So, at a frequency of 35 GHz,a typical output power value makes 100 mW, at an input power of 500 mWand multiplication ratio equal to 5. On a frequency of 94 GHz, an outputpower value attains 50 mW at an input power of 800 mW and multiplicationratio equal to 15. On a frequency of 140 GHz an output power value of 40mW has been achieved at an input power of 900 mW and multiplicationratio equal to 20.

INDUSTRIAL APPLICABILITY

The inventive engineering solution can be realized by an industrialmethod with use of known materials (microstrip line, polycore wafer) andknown technologies and hardware components (IMPATT diodes, clamps,tuning elements, waveguides), which, in the applicant's opinion, ensuresits compliance with the industrial applicability criterion.

The use of the inventive engineering solution, as compared with allknown means of similar designation, provides an output signal frequencyranging from 20 GHz to 180 GHz at an output power of several tens ofmilliwatts and a high ratio of input signal multiplication (ranging from3 to 30).

1. A frequency multiplier including an input circuit, embodied as acoaxial connector to input a signal to be multiplied, a means ofsupplying a signal to be multiplied to IMPATT diode mounted in aretainer, a means of supplying the diode with dc bias voltage and outputwaveguide frame, distinguished by the fact that the means of inputting asignal to be multiplied is embodied as a microstrip line formed on apolycore wafer and connected to a gold-plated strip which is connectedby welding to the diode, the means of supplying the diode with dc biasvoltage embodied as a quarter-wave filter formed by the microstripinductance and capacitance, the output waveguide circuit is embodied asa waveguide T-bend with an IMPATT diode arranged at the centre, twoshort-circuiting pistons fitted in two opposite arms and a pass-bandfilter disposed in the third arm.
 2. The frequency multiplier of claim1, distinguished by the fact that it is provided with a clamp whichenables adjusting the diode's position in the retainer by means of ascrew.
 3. The frequency multiplier of claim 1, distinguished by the factthat it is provided with a tuning plug which is fixed in respect to thediode by means of a split terminal consisting of a collet and a screw,the position of the tuning plug above the diode is regulated with thescrew.
 4. The frequency multiplier of claim 1, 2, or 3, distinguished bythe fact that it is provided with clamps to fix the position of twoshort-circuiting pistons fitted at two opposite ends of the T-bend. 5.The frequency multiplier of claim 1, 2, or 3, distinguished by the factthat the waveguide pass-band filter is embodied as two equal waveguide'ssections with a metal diaphragm nipped between them, and also isprovided with windows disposed along the axis of the waveguide which isformed by the said sections.